Back pack



FIG. 1 is a perspective view of a back pack embodying my invention;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a side elevational view thereof;

FIG. 4 is a side elevational view opposite that of FIG. 3;

FIG. 5 is a front elevational view; the crisscross configuration on the strap fronts being understood to be the same on the rear strap surfaces;

FIG. 6 is a top plan view; and,

FIG. 7 is a plan view from the bottom.

The broken lines shown throughout the views are understood to represent conventional stitching. 

The ornamental design for a back pack, as shown and described. 